This invention relates to a method of manufacturing laminated buses for use, for example, with substrates for printed circuitry.
Heretofore, buses of the type have usually been fabricated in the following way. As shown in FIGS. 1A and 1B, for example, sheet metal is perforated by punching to leave behind a plurality of conductor elements 2 in the form of parallel bands each having a number of terminals 1 extending widthwise at regular intervals. The conductor elements 2 have cuts 3 made at both ends so that they can be subsequently bent and torn off thereat from the rest of perforated sheet, or square outer frame 4. A number of such perforated sheets are prepared in this manner. The sheet shown in FIG. 1B is the same as the sheet of FIG. 1A except that the conductor elements 2A in this case have terminals 2A formed at intervals different from those of the former. The worker bends these perforated sheets by hand at the cuts 3 to sever the conductor elements 2 and 2A from the outer frames 4. Such cuts 3 may be replaced by necks 3A, formed by opposite notches as shown in FIG. 2, which may also be bent and torn off manually. The conductor elements 2 are thus severed one by one from the square outer frame 4 and, as shown in FIG. 3, the first of the elements is suitably placed on, and temporarily bonded to, a strip of surface insulating tape 7 broader than the elements 2 and 2A and which, in turn, rests on a surface portion of a jig 5 defined by pins 6 for positioning. Next, with the interposition of an interlayer insulating tape not shown, the other conductor element 2A is attached. This lamination procedure is repeated the number of times required. Finally, the resulting laminate is pressed and formed by heat sealing or other suitable means so that the excessive portions of the surface and interlayer insulating tapes are integrally bonded to the product, and a laminated bus with protruding terminals 1, 1A is obtained.
The aforedescribed method of the prior art is inefficient in that a number of the conductor elements 2, 2A must be first severed one by one from the porforated sheets and, for each laminated bus to be made, the temporary bonding and positioning for lamination of the elements are necessary. To be more exact, there are two major factors responsible for the inefficiency. One is that, in bonding the conductor elements 2, 2A to the surface insulating tape 7 and interlayer insulating tapes, care should be used to measure with the eye and leave equal spaces along the both edges of each element on each tape, as shown in FIG. 3. The other is that the edges of the conductor elements 2, 2A to be laminated with the interlayer insulating tapes should be trued up as precisely as possible.
In addition, the laminated buses thus obtained must be individually handled in subsequent operations which may sometimes be required, such as bending of their terminals 1, 1A, marking, and/or inspection. for these reasons the conventional technique can hardly give laminated buses at low cost due to mass production.